Cocaine abuse in human mothers is correlated with a high incidence of child abuse and maternal neglect. We have found that cocaine (COC) treatment decreased maternal behaviors (MB) and increased postpartum maternal aggression (MAG) towards an intruder. In rats, oxytocin (OXY) has been shown to induce the onset of MB and is thought to influence MAG. We have also observed that COC treatment in rat dams reduced levels of OXY in several brain sites thought to be important in MB (hippocampus) and MAG (amygdala). It has been found that OXY working perhaps through the dopaminergic system attenuates several COC induced behaviors. We hypothesize that COC will cause a significant change in the frequency, duration, latency or patterning of specifically designated MB and nonsignificant changes in non-MB rather than significant differences in only non-MB. We will measure frequency, duration, latency and sequence of maternal and nonmaternal behaviors in COC treated postpartum rat dams (Study 1). We also hypothesize that alterations seen in MB and MAG are not simply a result of withdrawal from COC. To test this hypothesis MB and MAG will be measured in postpartum rat dams under conditions of COC withdrawal and non-withdrawal (Study 2). To determine if the increase in COC-induced aggression towards an intruder is directly related to the postpartum endocrine state or contact with pups, we will study aggression in COC treated rats which are virgins, lactating dams with pups present and lactating dams without pups (Study 3). We hypothesize that COC induced increases in aggression are not dependent upon lactational state or pup contact. Studies 4 and 5 will help to determine if, as hypothesized, OXY and COC are interacting, through the dopaminergic system, to alter MB and MAG. To test this hypothesis we will: (1) attempt to block the effects of COC on MB and MAG with OXY (2) attempt to produce alterations in MB and MAG similar to those produced by COC treatment by administering an OXY antagonist (OTA) and a dopamine reuptake inhibitor (amfonelic acid).(3) measure changes in OXY binding, levels and release in COC treated rat dams and (4) measure dopamine uptake in rat dams administered OXY.